Event notification is managed in prior art solutions in a centralized way, i.e. around one (or a few) managers that collect information related to the events generated by the network elements (NEs), which are under its supervision. This centralised management paradigm is characterised by the concentration of the application processing and the traffic on a single network application whereas a collection of agents is limited to the role of dumb event collector. Due to the increase in the network size, there is a tendency to alleviate the load from a central management station by delegating some of the work load to agents, as counseled by the 3GPP long term evolution process. These agents are software entities that are run on remote NEs and perform tasks relating to event handling on behalf of the central manager.
A popular way of handling event notification lies in relying on the publish/subscribe paradigm in which consumers express their monitoring demands to producers during a subscription process and, in response to that subscription, the producers transfer to the subscribers notifications of events, which have been triggered locally.
From a communication point of view, a distributed publish/subscribe event notification system consists of exchanging notifications and control messages (i.e., subscriptions and un-subscriptions) between producers and subscribers through a collection of intermediate event routers.
When considering distributed event delivery, one can distinguish three main issues. First one that has to be resolved is the organisation (configuration and management) of the event delivery structure in the sense that the configuration and controlling of the delivery structure should be performed automatically. The second issue relates to the creation of an event delivery structure which is well balanced so as to ensure that the number of hops necessary to deliver a notification is bounded. The third issue is to ensure a fast dissemination of the event notifications over this structure.
Existing solutions to the above problem do not provide an adequate support to the above issues. Centralised, hierarchical or multicast-based event notification systems that are available assume that a network administrator configures statically their delivery structure. Such assumption prevents the system from being deployed over large-scale networks spanning sites distributed over large geographical area. In addition, the multicast-based event notification systems suffer from limited and sparse deployment of multicast protocols which is due to a combination of technical (complex billing, management and security concerns) and non technical reasons.
Other known solutions, like, for example, Distributed Hash Tables (DHT) event notification systems, exhibit self-deployment capabilities. However, their fully distributed delivery structure cannot be controlled or constrained with regards to some criteria (e.g., geographical position of group members, bandwidth availability, and role) which are relevant for aggregating or correlating notifications and hence improve the performance of the event system.
Hence, an improved method of processing event notifications and event subscriptions would be advantageous and in particular one that provides efficient structure of delivery event notifications, which keeps the number of messages exchanged to a minimum and which automatically reacts to changes in the network and changes in the demands of the event consumers.